1. Field of the Invention
The field of this invention is generally related to the topic of computer keyboards. More specifically this invention focuses upon keyboard design issues pertaining to ergonomic arrangements which permit the user to operate the keyboard in a standard fashion for data input to a computer, while achieving maximal adjustability to suit the user's anatomic requirements and ergonomic constraints. Improvements in these areas permit enhanced efficiency of key, manifest as improved speed and accuracy, while simultaneously minimizing upper extremity malpositioning and user effort and strain, which together may lead to repetitive stress injury, carpal tunnel syndrome and similar disorders.
2. Description of Related Art
For purposes of this application, the five digits on the hand may alternately be referred to as four fingers and a thumb.
Conventional contemporary computer keyboards, which serve as user-computer interfaces for such purposes as data and text input, trace their general design and functional characteristics to manual typewriters. Those earlier machines utilized mechanical linkages to convert finger pressure into symbols embossed upon paper. The functional mechanical design requirements of those typewriters produced a standard keyboard arrangement in which all keys were of similar size and were ordered in flat, parallel horizontal rows. Keys were not aligned in vertical rows, however, since the underlying mechanical linkages required that keys be offset with respect to keys in rows above and below. In order that all typed symbols achieve similar print density and appearance, it was necessary to apply the same vertical typing pressure to each key, regardless of which finger was utilized.
Mechanical linkages therefore dictated the fundamental arrangement and operation of keys. Typing, of necessity, required that fingers move to where keys were located and that they function as dictated by those mechanical arrangements. Little consideration was given to the functional anatomy of the fingers and hand.
Interestingly, many of the design characteristics of those original key arrangements and operations have been carried over, perhaps unwittingly, to conventional contemporary computer keyboards, even though the mechanical considerations which necessitated the original design are no longer relevant.
Both mechanical typewriters and contemporary computer keyboards share the following characteristics: a) the wrist and hand are not intended to rest upon any support while typing; b) each key is actuated by a downward pressing motion, regardless of where the key is located and which finger is utilized; c) keys are generally of similar size, shape and surface contour; d) key spacing is generally equal; and e) key tops define a typing surface which is level (or only slightly sloped) and generally continuous (i.e., key tops are not significantly elevated or depressed relative to each other). In addition, in both typing systems, key selection by the four fingers of each hand requires two kinds of motions: first, the fingers move through the air from key to key, often stretching to reach keys which are not within immediate reach and, second and simultaneously, the forearms, wrists and hands move in a subtly coordinated fashion to help position each finger in the appropriate location. Finally, the actual motions required to actuate the key selected are multiple and complex. They may include, at various times and in varying combinations, motions at the shoulder, elbow, forearm, wrists and the different finger joints.
Although widespread usage has demonstrated the functionality of current computer keyboards, these functional features of the computer keyboard have created a number of important problems, limitations and difficulties. These may be summarized as follows:
A. According to experts who study the ergonomics of keyboard usage, typing is optimally performed without resting or supporting any portion of either upper extremity upon the keyboard or supporting desk. Although occasional interludes for resting the wrists and hands are expected, the unsupported wrist, arm and shoulder can become tired during prolonged typing, and such fatigue increases both the mechanical stress on the limbs and the user's psychological stress.
B. The design of most keyboards necessitates that, for typing, the wrists be moved close together and turned outward (so-called ulnar or lateral deviation). Continuous muscular effect is required to maintain this position. Such an arrangement is therefore uncomfortable and stressful, and may contribute to carpal tunnel syndrome. More generally, any malpositioning of joints and tendons during keyboard use may be a factor in repetitive use injury.
C. The process of locating each key to be actuated in succession is difficult. Ideally, the user would combine visual and tactile cues to position each finger precisely for sequential key actuation. However, the technique of touch-typing directs the eyes away from the keyboard, to either the source material used for input of data or the CRT screen to monitor the information as it appears after input. Thus, tactile cues become essential for correct finger positioning for key selection and inadequate tactile cues about key location, and identity often becomes a limiting factor in user efficiency. Two aspects of tactile input are important in this regard:
1) the tactile determination of distance and direction for one key to another;
A lack of tactile cues about key to key distance and location occurs most frequently in the process of moving fingers from one distant key to another. As noted above, the hand and palm are not intended to rest upon the keyboard while typing, so they cannot provide any permanent geographic landmarks. The act of reaching up or down, and laterally or medially to actuate a distant key, often requires that the finger or fingers be lifted off their respective initial locations before moving to the next distant keys. This process eliminates most of the essential physical reference points between various fingers which facilitate determination of the precise distance and direction from one key to another. In essence, the user, through training and intuition, learns to measure distances and directions between keyboard points in terms of distance and direction between various regions of the hand. When one finger remains positioned on a first key, it is possible to use the hand to measure the correct distance and direction to the next key. However, when the user must lift the finger off the first key to reach the next, the initial point for measurement is lost, and the accuracy of locating the next key is reduced.
2) the differential tactile features of each key surface which may help to distinguish one key from another;
As the finger arrives near the destination key, recognition of the precise key location can be facilitated by the tactile features of the surface being touched. In most keyboards, the surfaces, shapes and contours of the various keys are identical. In addition, the flat keyboard surface lacks any geographic or topological landmarks or cues. Thus, key identification is impaired by the lack of any tactile features which would aid in distinguishing the desired key from adjacent ones.
D. The linear arrangement of key rows, combined with similar key sizes and constant key to distances, forces the smallest fingers reach the same distance and apply the same pressure for key actuation as required for the longest and strongest fingers. This situation, combined with the distorted orientation of the wrist described above, places excessive strain on the smaller fingers during key actuation.
E. The flat keyboard surface forces the hands and forearms to rotate inward (internal rotation), a position which tends to force the elbows up and out, increasing muscular effort and stress.
In sum, these characteristics place several limitations on the functionality of the keyboard. These limitations include:
A. The lack of hand and wrist support, plus the awkward hand, wrist and forearm position and difficult reach for certain finger-key combinations, cause significant stress on ligaments and tendons, promoting fatigue and increasing the tendency to repetitive stress injury.
B. The lack of adequate tactile cues, plus the need to select keys from a mid-air position, combined with the difficult reach for certain fingers, slow typing speed and increases the error rate for key selection.
Numerous modifications to individual aspects of the typewriter and computer keyboard have been introduced or proposed to address these issues. Several themes may be discerned in the prior art:
A. Improvement in the Positioning of the Hands.
Many arrangements have been disclosed which permit a separation of the keyboard into two halves by a variety of sliding, rotating or similar mechanisms or by creating two independent and unattached keyboard halves. This arrangement tends to lessen ulnar deviation of the hands. Other arrangements previously disclosed permit the adjustment of the keyboard position in one or more of three orthogonal axes, thereby influencing the degree of forearm internal/external rotation, wrist flexion/extension and wrist radial/ulnar deviation (Szmanda et al. U.S. Pat. No. 5,067,834; Rader U.S. Pat. No. 5,122,786; Fort U.S. Pat. No. 5,228,791; Fort U.S. Pat. No. 5,393,150; Danziger U.S. Pat. No. 5,426,499; Skovronski U.S. Pat. No. 5,457,452). However, in these latter arrangements, which utilize a ball and socket or similar mechanism, the center of rotation in each axis is displaced somewhat away from the center of the hand and of the face of the keyboard. Thus, when the keyboard is rotated by means of any of those adjustment methods, the hands and the keyboards are displaced varying distances forward, back, up, down and/or laterally. Thus, a second compensatory adjustment of the keyboard must be made to return the hand to its original spatial location and orientation relative to the body and the other hand.
B. Supports for the Wrists and/or Forearms.
A flat padded surface, situated at the lower edge of the keyboard, and intended for resting the wrist or hypothenar eminence when not typing, is available as an integral feature of many keyboards and may be obtained as a separate component for attachment to keyboards. In addition to providing some comfort to the user, this modification is intended to optimize wrist positioning, thereby reducing the likelihood of carpal tunnel syndrome. Several patents disclose arrangements to support the forearm while using a keyboard. In Danziger U.S. Pat. No. 5,426,499, a hand support is described. In Rader U.S. Pat. No. 5,122,786, a forearm rest is described; it has several adjustments for positioning the forearm, but does not provide for adjustment of wrist flexion/extension. Hargreaves et al. U.S. Pat. No. 5,689,253 and Johnson U.S. Pat. No. 5,730,403 show different methodologies for support of the palm while typing.
In Bryan U.S. Pat. No. 5,612,718, extensive consideration is given to positioning keyboard halves on the arms of a chair, with adjustments of keyboard position and some adjustments of an arm rest or arm support. Similarly, Litschel U.S. Pat. No. 5,627,566 shows two types of integral forearm supports, and Bryan U.S. Pat. No. 5,612,718 shows a variably adjustable chair with an adjustable arm assembly for support of the forearm.
C. Improvements in the Orientation of Keys Relative to the Fingers.
Prior art patents (Einbinder U.S. Pat. No. 3,929,216; Einbinder U.S. Pat. No. 3,945,482; Malt U.S. Pat. No. 4,244,659; Einbinder U.S. Pat. No. 4,332,493; Zilberman U.S. Pat. No. 5,156,475; Gambaro U.S. Pat. No. 5,178,477; Louis U.S. Pat. No. 5,302,040; Louis U.S. Pat. No. 5,372,441; and Hargreaves et al. U.S. Pat. Nos. 5,673,040, 5,689,253) have disclosed vertically curved keyboards, which presumably bring the upper row or rows of keys closer to the fingers, although this does not preferentially help the shorter fingers. One patent (Danziger U.S. Pat. No. 5,391,003) discloses snap-on keys of varying heights to create the desired curve. Another patent (Choi U.S. Pat. No. 5,481,263) attaches the keys to a curved vertical rib. None describes how the precise or correct curvature is established or determined.
D. Variation in the Size, Spacing and Orientation of Individual Keys.
Some inventions give varying degrees of explicit attention to key size and spacing. In Hodges U.S. Pat. No. 4,597,681 an “adjustable keyboard” is disclosed, built around keys whose height and angulation may be individually adjusted to reposition the rows of keys closer together or further apart. In Camacho U.S. Pat. No. 5,360,280, the center keys are elongated to accommodate a central curved area of the keyboard. In Minogue U.S. Pat. No. 5,397,189, slight variations in inter-key spacing are described, though the intent seems to be to achieve conventional distances. In Conway U.S. Pat. No. 5,410,333, the front and back keys are different widths, 18 vs. 15 mm. In Choi U.S. Pat. No. 5,481,263, the spacing between adjacent vertical rows (ribs) can be adjusted by sliding or pivoting the ribs. In Litschel U.S. Pat. No. 5,627,566, unique keys with multiple sensors are disclosed, in which the height and the key spacing are exactly fitted to the user's hand by means of an adjustment screw or with smaller or larger key units. No systematic discussion of the methodology for determining key spacing or key size adjustments is presented in those prior art patents.
A fundamental paradox arises in these design efforts. Critical analysis indicates that if any portion of upper extremity is supported during typing, the inherent mobility of the hand will be reduced. Since the current arrangement of keys is such that finger motions without hand movements are inadequate to reach many keys, the reduced mobility of the hand caused by the rest support will make typing even more difficult.
To the Applicant's knowledge, no patents disclose a keyboard arrangement specifically designed for use with a stationary hand or palm. Such a feature is desirable in a keyboard design.
Certain premises are inherent in the design and arrangement disclosed here. These premises are:
A. The wrists will rest on a comfortable support. This support may also involve contact with, and support of, the adjacent area of the palm, but for simplicity reference is solely to a wrist support. Supports for the forearm may also be optionally supplied.
B. The wrist support will permit the entire upper extremity to be oriented in any comfortable and ergonomically correct position. This position, with the forearms somewhat separated, is described with reference to rotation relative to the length of the forearm (internal/external rotation), and with respect to up/down (flexion/extension) and left/right (radial/ulnar deviation) position of the wrist. By necessity, the best position will be somewhat different for each user; hence, this keyboard invention incorporates adjustability of the wrist support to permit the wrist to rest to any comfortable and ergonomically appropriate position.
C. The hand and digits will rest naturally in comfortable and ergonomically correct positions. Conventional keyboard arrangement forces the hand and digits to lie almost flat, on a single plane or surface. Casual inspection indicates that the thumb flexes and extends along a plane perpendicular to the flexion/extension plane for the other fingers. Further, when at rest the tips of the fingers do not naturally lie along a single straight line but describe a curve reflecting the different lengths of the fingers. Thus, an ergonomically correct rest position (or “home” position) for the hand will require home row keys which are oriented in unconventional positions and directions, i.e., different from those found in conventional keyboards.
D. Key actuation will require only natural, ergonomically appropriate motions of the digits alone. This feature follows logically from the previously described features. Since the wrists (and possibly the adjacent palm areas) are supported, maintained in a stationary position and not intended to be mobile, only digit motion is possible. Key arrangements are therefore necessary which enable key actuation by finger motions which are comfortable and easy, and which do not require difficult reaching, stretching or twisting of the fingers. In essence, keys are positioned where the fingers can naturally and easily reach them for key actuation.
Several advantages of such an arrangement may thus be identified as:
A. Arm, forearm and wrist are positioned and supported in comfortable and ergonomically correct positions, lessening stress and decreasing the likelihood of repetitive stress injury.
B. These arm, forearm and wrist positions can be adjusted to suit each individual user.
C. By requiring only digit motion for key actuation, the chance of key selection error is reduced, since the wrist and palm remain as stationary reference points as the digit seeks out its target key.
D. The rest positions for the digits, and the motions utilized for key actuation are comfortable, easy and ergonomically sound, lessening the effort, degree of stress and likelihood of repetitive stress injury and keystroke errors.
However, certain problems and difficulties may be discerned when one attempts to superimpose such a keyboard arrangement upon previously disclosed keyboards. These problems and difficulties are:
A. Existing keyboard surfaces are flat or only mildly contoured. Even in the most contoured keyboards, the longer fingers are closer to the surface of the keyboard than the shorter fingers of the same hand, making it more difficult for the shorter ones to reach and actuate keys. This effect is enhanced as the fingers move up and down or laterally to actuate keys which are equally spaced from each other. It is further exaggerated by the requirement that the wrist and palm remain stationary, forcing all fingers to do excessive stretching to reach more distant keys.
B. Even if an arrangement can be established which positions keys at an appropriate distance from the finger tips of the average user, this arrangement may not be suitable for other users with different hand and finger sizes.
C. When a keyboard is split into right and left sections which are separated from each other and then tilted or angled to suit the user's comfort, most keys will not be visible; hence, visual cues used for locating keys will be reduced or eliminated, increasing the difficulty of key selection.
D. By requiring only digit motion for key actuation, the muscles of the weaker digits (i.e., ring and short fingers) are required to provide the same force for key actuation as corresponding muscles of the stronger digits.
To address these additional issues, this invention discloses a methodology for defining the maximal and minimal reach of each finger while the palm is stationary. This involves tracing the arc of the finger tip as it moves up and down (“vertically”) through varying degrees of flexion and extension of the MCP (metacarpophalangeal, [knuckle]), PIP (proximal interphalangeal, [finger joint nearer to knuckle]) and DIP (distal interphalangeal) joints. These motions define a space bounded by two arcs, representing the maximum and minimum reach for each finger. Within this space the surface of all keys for a specific finger may be appropriately placed for comfortable, ergonomic usage. If the keys are farther away, they cannot be reached with a stationary palm; if they are closer, then they will be bumped as the finger moves up and down to actuate other keys.
When keys are positioned according to this arrangement, the result is a curved, vertical array of keys for each finger. When these arrays are arranged side by side as described in detail below, the result is a keyboard that is complexly curved but with each key precisely positioned for optimum ergonomic usage.
The methodology disclosed in this invention extends the art beyond what has been disclosed in prior art patents known to the Applicant. Those patents assume that keys can be placed appropriately but do not specify how this may be accomplished.
This invention discloses key positioning such that actuation is accomplished by the full swing of each finger while the palm is immobile. Specifically, the range of motion is envisioned to utilize the MCP as well as the PIP and DIP joints of each finger. In Choi U.S. Pat. No. 5,481,263, a somewhat related arrangement is disclosed, but utilizing finger motion only at the PIP and DIP joint; no motion of the MCP joint is shown or suggested.
This invention also describes an arrangement in which a top key may be actuated by the finger as it sweeps in full extension, with the fingernail, or any region of skin on the nail side of the finger actually striking and actuating the key. This arrangement provides an additional group of potential key placement sites and increases the flexibility of the keyboard and the number of keys which may be included. A soft key surface may be used to cushion the impact of the hard nail.
Actuation of a key with the back of the finger has been suggested or shown elsewhere.
An arrangement has been disclosed (Yaeger U.S. Pat. No. 4,584,443) which places each finger tip in a cup; extension or outward motion is used for “key” actuation, although the key itself is not a conventional key. In Allen U.S. Pat. No. 5,486,058, actuator switch caps are disclosed with three flat surfaces, one, horizontal for actuation by downward motion, and two, nearly vertical, for actuation by inward or outward motion of the finger, respectively. Runge U.S. Pat. No. 4,265,557 discloses an arrangement for key actuation through mechanical linkages actuated by slight extensor or flexor motions of the fingers, with the opposed key surfaces being closely approximated. Horn U.S. Pat. No. 5,552,782 discloses an arrangement of two parallel horizontal supporting surfaces, with keys arrayed on the inner, facing surface of each, and the hand placed between. Downward motion actuates keys on one surface, and upward motion the keys of the other. A curved array of keys is not used in this arrangement. Use of multiple different areas of the back side of the finger, including the nail, is disclosed in Litschel U.S. Pat. No. 5,627,566. In this arrangement minimal finger motion is permitted, and only one or two keys for actuation with finger flexion or reach is disclosed. A full swing of the finger is not envisioned.
This invention specifically positions the thumb in a rest position in which it is separated from the index finger and rotated outward, so that the natural flexion of the thumb brings the thumb first toward the side of the index finger and thence toward the palm. As a consequence of this arrangement, a number of keys may be positioned such that they may be actuated by natural, comfortable and ergonomically appropriate motions of the thumb. These motions include:
1. Thumb flexion and extension, utilizing, respectively, the thumb flexor muscles and ligaments, and the thumb extensor muscles and ligaments. Several keys may thus be actuated with this arrangement, including by application of pressure by the nail or extensor surface of the thumb during thumb extension.
2. Thumb adduction and abduction, i.e., moving the thumb in a plane perpendicular to the plane of thumb flexion/extension, thereby bringing the thumb toward or away from the side of the index finger. One or more keys may be readily actuated by each of these motions.
3. Some combination or combinations of thumb flexion/extension and abduction/adduction.
This combination of rest thumb position and the thumb motions described above for multiple key actuation is featured in this invention.
The prior art includes many patents which describe multiple thumb keys (Einbinder U.S. Pat. No. 3,929,216; Gopher et al. U.S. Pat. No. 5,493,654; and Torok U.S. Pat. No. 5,485,425). Some describe thumb key positions which require for key actuation one or more orthogonal thumb motions as described immediately above (Einbinder U.S. Pat. Nos. 3,929,216; 3,945,482; and 4,332,493; Retter U.S. Pat. No. 4,913,573; Allen U.S. Pat. No. 5,486,058; and Klauber et al. U.S. Pat. No. 5,626,427). In all of these, however, the thumb position at rest is on the same surface as the fingers, in contrast to this invention in which the natural thumb position (i.e., away from and rotated relative to the rest of the hand) places the thumb tip out of the plane of the other digits.
In other patents (Dolenc U.S. Pat. No. 4,849,732; Mohler et al. U.S. Pat. No. 5,160,919; Nikisbacher U.S. Pat. No. 5,270,709; Gambaro U.S. Pat. No. 5,332,322; Grant U.S. Pat. No. 5,339,097; Rucker et al. U.S. Pat. No. 5,351,066; Conway U.S. Pat. No. 5,410,333; Danziger U.S. Pat. No. 5,426,449; and Litschel U.S. Pat. No. 5,627,566), thumb keys are arranged for actuation such that the thumb is allowed to move away from the hand and rotate so that its natural flexion motion would bring it toward the side of the index finger and with further flexion toward the palm; this is the same thumb rest position as described in this invention. Yet, in almost all of those patents, the thumb keys (and the associated motions for key actuation) are co-planar rather than orthogonal to each other, so that no key motion utilizes thumb abduction or adduction as the sole motion. In one patent (Yaeger U.S. Pat. No. 4,584,443), an arrangement similar to that disclosed herein is suggested; however, it is qualitatively different in that the thumb and fingers rest within rings or cups and do not rest upon keys. In another patent (Horn U.S. Pat. No. 5,552,782), a related arrangement may be suggested, but the figures and text are insufficient to provide a clear description or explanation, and the emphasis is elsewhere.
This invention discloses the inclusion of a joystick, pointer, tracker ball or similar cursor controller device in place of a key, between the keys, or as the whole keyboard itself (i.e., sliding the keyboard across the table top serves the same function as moving a mouse). Multiple patents have addressed these issues (Rader U.S. Pat. No. 5,122,786; Zilberman U.S. Pat. No. 5,156,475; Grant U.S. Pat. No. 5,339,097; Conway U.S. Pat. No. 5,410,333; Ullman U.S. Pat. No. 5,411,341; Grant U.S. Pat. No. 5,416,498; Danziger U.S. Pat. No. 5,426,499; Gervais U.S. Pat. No. 5,508,719; Selker et al. U.S. Pat. No. 5,521,596; Sellers U.S. Pat. No. 5,594,618; Litchel U.S. Pat. No. 5,627,566; and Retter U.S. Pat. No. 4,917,516). This invention advances the art relative to those prior disclosures by making it possible to reach and actuate any joystick, tracker ball, pointer or similar device incorporated within the key region or as part of the keyboard base, while maintaining the wrist and palm stationary and at rest, and hence without moving the hand from its typing position.
This invention discloses an arrangement in which the force necessary for key actuation may be variably reduced to account for the weaker muscles utilized for key actuation by the smaller fingers. Uke U.S. Pat. No. 5,676,476 discloses an arrangement in which keystroke resistance is (apparently) increased to 100 grams for all keys.
This invention discloses an arrangement in which multiple tactile cues associated with keystroking surface characteristics are utilized to enhance the user's ability to identify each key in turn for actuation. Miller U.S. Pat. No. 5,660,488 discloses a simplistic version of such an arrangement in which a protrusion is formed on a finger contacting surface of each key.
This invention discloses an arrangement in which a contoured sheet of flexible material is positioned upon the keyboard to alter the height of the keys relative to the finger tips. A similar arrangement for a planar keyboard is disclosed in Caplan U.S. Pat. No. 5,899,616.